Field of Invention
Various embodiments of the inventive concept of the present disclosure relate to a semiconductor optical device, and more particularly, to an optical waveguide structure.
Description of Related Art
An optical waveguide structure provides an optical transmission path for optical signal transmission. Various methods for processing an optical signal have been developed in the field of optical communications using optical signals. For example, a semiconductor optical device in which a high output light source capable of transmitting a high-speed optical signal at a long distance and an optical modulator operating at a high rate are integrated into a single unit, such as an electroabsorption modulator integrated DFB laser (EA-DFB), has been developed. A waveguide for high optical output characteristics and low threshold current characteristics may have a different structure from a waveguide for high-speed modulation characteristics.
As described above, when an optical waveguide structure is implemented by combining different types of waveguides, a difference in optical mode size and a difference in effective refractive index may occur due to the structural difference between the different types of waveguides. Therefore, when a single integrated optical device is manufactured by combining different types of waveguides, optical loss in the optical device may be increased due to the difference in optical propagation mode between the waveguides. As a result, optical output of an optical device may be deteriorated. In addition, the difference in effective refractive index between the different types of waveguides may result in optical refection in the optical device. The optical reflection in the optical device may interfere with wavelength stabilization of the optical device and deteriorate yield of the optical device.